Spiral seamed pipes made from strips of sheet metal are widely used to transport fluids. For example, these pipes are frequently used to transport air in order to ventilate, heat and cool buildings. In this application, as well as others, it desired that the pipe produced is strong, lightweight and inexpensive, and provides minimum resistance to fluid flow. The pipe must be sufficiently strong to maintain rigidity over long expanses and against pressure from external forces. Any aberration in the uniformity of the inner pipe surface, such as bends or dents, increases the resistance to fluid flow through the pipe. It is desirable for the pipe to be lightweight so that less manpower is required to carry and install it.
In the past various U.S. patents have issued for devices relating to the formation of spiral pipe. U.S. Pat. No. 4,567,742, issued on Feb. 4, 1986 to W. P. H. Castricum, describes a ribbed spiral pipe producing machine. This machine includes conventional elements of a frame, a drive roller for feeding the strip through the frame, a flange roller and folding finger for bending the outer edges of the metal strip, a forming head for forming the strip into a pipe so that the outer edges of the strip mate, and a clenching roller and contra roller for compressing the mated edges to produce a spiral seam. This patented device improves on conventional apparatus by providing only two pairs of edge forming roller assemblies that cooperate to bend the left edge of the strip perpendicular to the strip, and the right edge of the strip into an upward facing, V-shaped channel with its outer edge perpendicular with respect to the stip.
U.S. Pat. No. 4,924,684, issued on May 15, 1990 to W. P. H Castricum, describes a apparatus and method for forming and cutting spiral pipe. The pipe forming apparatus includes an enclosed forming head and a mandrel. A continuous strip of metal is driven around the mandrel and inside a lateral bore in the forming head in a helical manner. First and second rollers are mounted in the forming head so as to partially form a spiral lockseam. A third roller is mounted in the upper portion of the forming head so as to close the spiral lockseam. The mandrel is both rotatable and pivotable.
U.S. Pat. No. 5,105,639, issued on Apr. 21, 1992 to W. P. H. Castricum, also discloses an apparatus for forming spiral pipe. In particular, this device is configured for forming spiral pipe having a diameter of approximately one inch or less. A continuous strip of metal is driven around the mandrel and inside a lateral bore in the forming head in a helical manner. First and second rollers mounted in the forming head partially form a spiral lockseam. A third roller mounted in the upper portion of the forming head closes the spiral lockseam. Various knives are employed so as to sever the pipe as it rotates.
U.S. Pat. No. 5,609,055, issued on Mar. 11, 1997 to W. P. H. Castricum, teaches a method and apparatus for cutting and notching a hollow pipe. This apparatus includes a upper knife assembly having a pipe cutting knife and notch cutting knives with cutting edges adjacent a surface of the pipe and a lower knife assembly having a pipe cutting knife and notch cutting knives with cutting edges adjacent an opposite surface of the pipe. The method of this invention includes stopping the axial and rotational movement of the pipe and moving the lower knife assembly into an overlapping relationship with the upper knife assembly. The notch cutting knives are also moved into cutting position and the axial and rotational pipe movement is resumed.
U.S. Pat. No. 5,636,541, issued Jun. 10, 1997 to W. P. H. Castricum, also teaches an apparatus for forming and cutting spiral pipe having a diameter of less than one inch. The device for slitting the spiral pipe into sections includes a first knife that is positioned inside the spiral pipe and a second knife that is positioned outside of the pipe. A support sleeve is also positioned outside of the pipe and is in a fixed radial position with respect to the pipe. The inner and outer knives and the support sleeve move axially with the pipe as the pipe is severed.
The conventional spiral pipe forming machine is manufactured by Spiral-Helix, Inc. of Buffalo Grove, Ill. On this device, a forming head is positioned on the machine so as to extend outwardly of a frame portion. Conventionally, the forming head is of a relatively small diameter so that relatively small diameters of ductwork can be formed through the use of such spiral pipe forming process. This ductwork is often used for the passing of ventilation, air conditioning and heating within a building or a very large vehicle. The forming rollers associated with the forming head are positioned adjacent to an outwardly extending frame portion. As such, the maximum diameter of forming head that can be accommodated in such machines must be less than seventy-eight inches in diameter. If the spiral pipe is of oversized diameter, then other techniques are required for the creation of such large diameter ductwork. Conventionally, when such oversized ductwork is required in a particular project, the oversize ductwork is not formed through the use of the spiral-Helix machine, but rather through complicated seam welding processes. In other words, the large circular portion of the ductwork are formed on a roll forming machine. Each of these circular sections is then joined and welded together in end-to-end relationship. This process of forming such oversized circular pipe is extremely expensive, requires a great deal of manpower, and is relatively inefficient. Unfortunately, none of the existing machines have the capability of creating such large diameter spiral pipe. Inevitably, if a forming head of such diameter were utilized on the Spiral-Helix machine, then the edges of the circular forming head would contact the frame portions of the machine and prevent adaptation and use thereof. As such, a need has developed so as to create a forming head by which such large oversize diameter spiral pipes can be formed by using such Spiral-Helix machines. Additionally, there is a need in the art to provide the ability to create such oversize ductwork through the use of a spiral forming process rather than seam welding and roll forming.
The requirements to manufacture such large oversize diameter ductwork are particularly important in view of the expanding market for such oversize ducts. Larger athletic facilities are being created throughout the world. These athletic facilities often require the transport of air conditioning and heating to the spectators at the stadiums. As a result, there is a need to transport extremely large volumes of air conditioned or heated air from one location to another within the stadiums and athletic facilities. In other circumstances, larger and larger buildings are being built for manufacturing facilities, entertainment facilities and residential facilities. In view of the size of these large buildings, it is desirable to have such oversized ducts for the transport of large volumes of air from one location to another. Still, and in addition, there is a further requirement to have air conditioning and heating facilities at one location while the requirements of use of such air conditioned or heated air are at a remote location. Once again, there is a need for oversized ducts for the transport of such large volumes of air. There is a need at the present for the creation of such large ductwork through the spiral forming processes associated with previously small diameter ducts.
Typically, forming heads used for the creation of such circular pipe are relatively expensive. These forming heads are typically roll formed of steel or aluminum material. The forming heads must be sufficiently strong so as to withstand the forces associated with the formation of the spiral pipe. In certain circumstances, minor adjustments in the diameter of the spiral pipe are necessary after the forming head has been manufactured. If minor adjustments to the diameter of the circular pipe are required, then the previously manufactured forming head must be scrapped and a new forming head created. As such, a need has developed so as to be able to adjust the diameter of the forming head with minimal cost and inconvenience. Additionally, where the forming head is of a relatively large diameter, a need has developed so as to avoid deflections in the large diameter of the forming head.
It is an object of the present invention a method and apparatus for the forming of oversized circular pipe which utilizes spiral forming procedures.
It is another object of the present invention to provide a method and apparatus for the formation of oversized circular pipe which can utilize the Spiral-Helix machines.
It is another object of the present invention to provide a method and apparatus for the formation of spiral pipe which provides the ability to form spiral pipe having a diameters of greater than forty-eight inches without offsetting the forming head.
It is another object of the present invention to provide a method and apparatus for the spiral pipe formation of circular pipe which minimizes the costs and labor required for such sections of circular pipe.
It is still another object of the present invention to provide a method and apparatus for the formation of circular pipe which allows the forming head to be adjusted between diameters without significantly increasing the cost of the forming head.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.